Digesting and cooking liquor preparation system



May 26, 1931. A. DA MERRILL DIGESTING AND COOKING LIQUOR PREPARATION SYSTEM Filed June 24 1950 5 Sheets-Sheet 1 gmmntoc Hernia fr. @mf

Mah. NSW Q @i May 26, 1931. A. DA MERRILL DIGESTING AND COOKING LIQUOR PREPARATION SYSTEM .WASH

May 26, 1931. A. D. MERRILL 1,807,320

DIGESTING AND COOKING LIQUOR PREPARATION SYSTEM Filed June 24 1950 3 Sheets-Sheet me QN (QL. WJDDOUY wwzwhn A', Merrill mi mwy abbauen Patented May 26, 19:31

UNITED STATES PATENT oi'fiucla.I

maar ravine Hanru.. or warnwrown, maw Yom: mans'rnro Ami 00eme' manon. rmanurxon mmm: application mea une a4. im. lterm no. agua This invention relates 'to the manufacture of paper pulp, and more es ially to anovel s stem for making the aci liquor used in the igestion of lfibrous material, and' for recov- 5 ering the heat units and gases from digesting systems.

t is customary in pulp plants to employ an acid preparation s stem from-'which the acid liquor is supplie to the digesting system, and the primary object of the resent invention is to provide a new t 1e plant which will avoid the necessity o having an acid system. In other words, in accordance withy my invention, the acid liquor is prepared in the digesting system, and the accumulators of the digesting system are einployed for the accumulation of acid liquor, se

A as to avoid the use of a separate acid system.`

Pursuantto' m invention, the digesting system is rovide with at least two accumulators, ei er one of which may operate, asa

high pressure or a low pressure accumulator,

whereby the accumulator may be used alternately, first for high pressure purposes, and second, for low pressure urposes. To this end, a distributor arrange at the lower lpor tion of each accumulator, is connected y a pair of down ipes, to the high pressure header and the ow pressure header, so that gas, vapor or liquid from either of these headers may be fed 1into the accumulator. Each of these down pipes is also connected'by a l valved'conduit to'the top portion 'of its re- 35 spectiveaccumulator, so that` gas escaping from the top of an accumulator, may be fed directly back into the lower portion of the same accumulator.

Furthermore, the system is such that SO, gas from a storage chamber may be fed into any one of the down pipes. l

In addition, each down pipe is connected to a milk of lime tank, so that milk of lime Y ma be contacted with the S0, 'gas as well as 46 wit gas, vapor or liquid from the digesters,

-poin on its way to one or the other of the accumulators. 1

' A further object of. the invention is to ro vide a` system of this character, in w 'ch ses from the accumulatore ma flow into-w temilkoflimetanktobeabso bythe milk of lime in said tank. Another object is to furnish such a stein in which the pipes which lead the S gas and the milk of lime to the down pi are inter-connected by a valved conduit, by which the lgas ma;7 be mixed with the milk of lime whi e the atte;` is on its way to the down pipes.

A still further .object is to provide such a system in which the SO, may be led from a storage tank into the ower end ofeitheri one of the accumulatore.

Another object is to furnish an apparatus of this type in which the acid liquor made in he accumulatore is heated by hot gas, vapor or 1i 4uor coming over from the di where y the hot fresh precondition liquor may be subsequentrl pumped into a di' that has just been ed with chips lfor immediately starting the cooking operation in the latter digester.

With the foregoing objects outlined and with other objects in view which will appear as the description proceeds, the invention consists in the novel features hereinafter de scribed in dla'isdetail, illuslrated .in tl acorlnpanyin1w1n,anjmore a c ary' tedg out in t e appended Referring to the drawings,

Fg. 1 is a side elevation of my improved ap aratus.

ig. 2 is a top. 5mn view of the same.

8 is ya data vertical sectional view on the line 8-3 of Fig. 2.

Fi-is a similar view of a detail on the line of Fig. 2. y

Fig. 5 is a sectional .vew, of a detail show in one .of the injector littins' for eedin m oflimeacrossoneoftereliefui 00 headers into one of the down pipes leading into one of the accumulatore.

4In all of the gures of the drawings, the apparatus is diagrammatically shown, due to the fact that the multiplicit of pipes used makes it neceary to alter t e actual positions of the pipes, so that they may be readily seen in the drawings In the drawings, 1, 2 and 3 deslgnate conventional digesters, and 4 and 5 indicate pressure accumulatore. While I have shown three di esters and two accumulatore, it will, of course, be understood that one or more digesters may accumulatore may be emplo ed.

6 designates a'storage tan for liquid SO2 which is held in the tank under a pressure of from thirty to one hundred pounds per square inch. 7 is a closed milk o f lime tank, and 8 represents two lime slackers.` An abso tion tower is shown at.9.

e digesters are provided with to relief branches 1a, 2a, and 3a, each of w 'ch is branched as at 10 and 11, the branches being provided with valves 10a and 11a.

The side relief pipes 1 2a, 3a, each having a control valve 12, lea from the sides of the digesters into the to relief pilples and the branches of the latter ead to the gh .and low pressure headers 13 and 14.

' These headers communicate with down ipes 15, 15a, 16 and 16a, the low premure header being in direct connection with the pipes 15 and 15a, and the high pressure header being in direct connection withthe pipes 16 and 16a, but as best shown in Figy3, valves 17 and 18 are arranged in the -down pipes to control the passage of the relief fluids from the low and high pressure headers to the accumulatore.

Each pair of down pipes 15, 16 and 15a, 16a, are connected at their lower ends to a dis tributor 19 that has valve controlled nozzles 20, leading into the accumulator from various oints.

e top of each4 accumulator Ais joined to the respective down pipes of that accumulator by a branched conduit 21,'that is provided with a lrassure operated valve 22, whereby-when t e pressure in an accumulator reaches'a. predetermined degree, gas from the accumulator may flow through theconduit 21 directly back into'its down pipes.

Other conduits 23 having pressure 'ac tuated valves 24v therein' 'are connected' together,

and empty into 'a 'pipe 25 which leads to the lower portion of4 the milk of Alime tank, so that any gases through the pipe 25 mavhe absorbe by the milk of lime in the ta .7. In case theabsorption should not be com discharge from the tank t rough a. ipe 26, intov the absorption tower 9, down w ich milk of lime from the tank is showered. This showering is accomplished inthe following be used, and that one or more Y way. A ump 27 draws milk of lime from the tankA through a pipe 28, and feeds the same through a pipe 29, into the top of the tower. The upper ortion of the latter is provided with a pe orated distributor plate 30 which causes the milk of lime to evenly distribute and spray downwardly over contact blocks 31, whlch substantially ill the absorption tower.

It will be understood that the valves 22 or 24 may be so loaded that under ordinary circumstances, gas gatherin in the accumulators will simply How bac into the down pipes of e aecuxnulators,l but if the pressure should build up to a redetermined maximum, then the gas woul open one or the other of the valves 2 4,a nd the gas from the accumulator would be discharged into the milk of lime tank- Ai i 32 having a hand controlled valve 33, ee' j the liquid 'S02 to a coil 34, arranged in a -vaporizing' tank 35, and from the coil, the Iva'poriz'ed `S02 passes toa conduit 36. l

When the atmospheric temperature is high, the liquid SO2 will vaporize 1n the coil without the use of anyehea-ting agent, butin cold weather it will necessary, to feed steam or the llke through the vaporizer casing by any suitable means, such as valved conduits 37.

The vaporized SO2 may be introduced into the milk of lime'in either 'one of the 'accumu-v lators, by passing the SO2 into the bottom of the accumulator by way of"'a. pipo 38 which has valved branches 39 and 40connected to the accumulatore.

In order te pass the'milk of lime to the accumulatore, a pump '41 draws the milk of lime through a pipe 42 and forces the same through a-pipe 43, the latter bein connected by valved ranches 45,46, 47 an 48, as best shown in Figs. 2 and 3, to the low and hh pressure headers immediately above t e down pipes 15, 16, 15a and116a. l

en desired, thevaporizedSO, from the pipe 36 may be mixed-with the milk of lime while it is owi-ng throughA the -pipe 43,v and for this purpose, the pailpes 36 and 43 com'- municate by way of a v ed by-pass pipe 49.-

Instead of us'mgfthe by-pass 49, the va v ized SO, maybe mixed with the milk of ime after the latter has come into contact with relief fluids froxln'the headers 13, 14, and to accomplish this, the pipe 36, asbest shown in Fiv 2, is branched at its Vupper end to provi e conduits 50 and 51, having hand .controlled valves. 52 and 53. The conduit 50 is joinedto the down pipes 16 and 16a by means of valved branches 54 and l55, and the conduit 51 isconnected to the down pipes 15 andlabysixnilar branches 56 and 57. v

Acid liquor which has been made and preheated in my system, is discharged from the accumulatore through valved conduits 60 and 61, which are joined to a header 62, from which the preconditioned liquor is drawn by a pum 63. The latterforces the liquor througi a header 64 that is connected by valved conduits 65 to the lower ends ofthe digesters.

In proceeding in accordance with my invention, common ordinary burned lime is dumped into the mixer 8, and water is admitted to' the same, then by operating the agitators in these mixers, the lime is thoroughly slacked, and afterwards discharged directly into the tank'7. Two slackers 8 are shown, so that one can be slacking while the other is discharging, and in this way, the process is continuous. Of course, for small plants, only one lime slacker will be required.

The milk of lime is fed from the tank 7 by way of the pump 41, into the accumulator, which, at the time, is functioning as a low pressure accumulator, and is receiving relief fluids from the low pressure header 14. At such time, let us assume that the valves are properly set, so that the low pressure relief fluids are fed into the down pipe 15 of the accumulator 4, which, at the time, is working as a. low pressure accumulator, while the accumulator 5 is o erating'as a high pressure accumulator, an is receivin high pressure relief fluids by way of the own pipe 16a. At such time,'milk of lime will be orced by the pump 41., through theconduit 43, and by way of the valved branch 46, it will be caused to descend in the down pi e 15. Consequently, it will be mixed with t e low pres sure relief fluids in this down pipe.

At the same time, the system provides three ways of introducing the va-porized SO2 into the milk of lime. First, it may be fed from the pipe 36, through the valved conduit 49, into the pipe 43 while the milk of lime vis flowing through the latter.

Second, it may be passed through the conduit 51, and its valved branch 56, into the 'down pipe 15 to mix in the latter with the milk of lime and the low pressure relief fluids.

Third, the SO2 may be directly introduced .into the bottom of the accumulator 4 (low pressure), vby means of conduit 38 and its valved branch 40.

- While I prefer to separatel use any one of these three modes of proce ure, of course,

.such' acid liquor is heated up by high ressure relief fluids from the digesters. At t is time, we will assume that acid liquor in the high pressure accumulator 5 has been heated up to the desired degree to be used as a preconditioned and preheated liquor in a digester which has just been charged with chips or other fibrous material. At such time, the valve in the ipe 61 is opened, and the pum 63 is used to orce this hot acid liquor' throug 'the header 64 and the proper one of the valved branches 65, into the digester which has just been charged with chips.l

When the accumulator 5 has been emptied, it becomes the low ressure accumulator, and the accumulator 4 ecomes the high pressure one. Consequentl the valves are manipulated to place the own ipe 15a in communication with the accumu ator 5, and the down pipe 16 of the high pressure header into communication with the accumulator 4. At the same time, the flow of SO2 from the tank 6 and milk of lime from the tank 7 is cut offz from the accumulator 4, and chan ed over to the accumulator 5. To this end, t e valve in the branch 48 of the milk of lime pipe is opened, and the valve in the pi e 46 is closed, and of course, the va orize SO2 can be mixed with the milk of ime going to the accumulator 5 in an one of thethree ways heretofore mentione While the acid liquor is being manufactured in the accumulator 5, and the latter is receiving the low pressure relief fluids from the header 14, the acid liquor in the accumulator 4 is beine' heated up by the hot relief fluids from the eader 13, and is absorbing some of the SO; coming over from the digesters. I 'A When either one of the accumulatons is on the high pressure period of its cycle, of course the pressure builds up therein and must be relieved. Ordinarily, the pressure controlled valve 22 will simply relieve gas from the high pressure accumulator back into the down pipe of that accumulator which is in communication at the time with the high pressure header 13, but where Athe pressure goes beyond a predetermined maximum, it will open the valve 24 and will relieve the gas back into the milk of lime tank 7. If it is not entirely absorbed 'in the latter, it will pass through the pipe 26, into the absorption tower 9, where it will meet the milk of lime showering downwardly, and will be completely absorbed.,

For the purpose of using the pumped milk of lime to induce the flow of the relief fluids, and vice versa, I prefer to place an injector fitting or nozzle (Fig. 5 at each point where the milk of lime branc pipes join the high and low pressure headers at the upper ends of the down pipes 15, 15a, 16 and 16a. In a small plant, only one accumulator will be required, and milk of lime will be pumped continuously into this accumulator, and the as from the tank 6 will be conducted to the ischarge side of this pump by way of conduit 49, so that the liquor and gas will be well mixed and then flow to the accumulator.

Instead of usin milk of lime, I may mix a soda solution wit the SO2 for making the cooking liquor. In the case of producin the sodium bisulphite liquor, it will probab y be advantageous to make up a cooking liquor of the following analysis lOtal SO2 i 5% Combii'ied S02 2% Free SO2 3% Calcium oxide, Ca() 58.61 Magnesium oxide,MgO 40.25 Alumina and ferric oxide, A120, and F6203 1.; Sulphur trioxide, SO,l 0.15 Insoluble in HCl 0.07 Silica soluble in acid, Si02 0.15 Loss on ignition, H2O, CO2 etc 0.51

In the above analysis of burnt lime ordinarily used, I have of course merely given an average analysis, as these limes vary considerably, sometimes running as low as 35% of magnesium oxide and 58% or 60% of calcium oxide. Also occasionally, a lime-of ve hi h calcium oxide content is employe Wen dolomite is used, the magnesium con tent runs as high as 46%- with a consequent reduction in calcium content and occasionally ground magnesium oxide is used in place of calcium. Tlliis ground magnesium oxide runs very high' in magnesium content.

My cooking liquor ma have a combined calcium and magnesium ase, practically all calcium base, sodium base orpractically all ma esium base.

rom the foregoing it will understood that I not only employ the accumulatore for their usual work of absorbing gas, conserv ing heat units and preconditioning acid li uor, butin addition, they actuall form the acid storage tanks, and thus ena le me to hook-up the digesting system and the acid preparation system in such a way as to eliminate part-s heretofore considered absolutely necessary for successful working.

While I have disclosed what I now consider to be a preferred embodiment of the invention in such manner that the same may be readily understood, by those skilled in the art I am aware that changes may be made in the details disclosed, without departing from the s irit of the invention, as expressed in the c aims.

What I claim and desire to secure by Letters Patent is:

1. A method of the character described, comprising feeding milk of lime to a pressure accumulator, conducting SO2 to theaccumulator contactingl these substances to make acid liquor, and mixing a digester relief fluid with such acid liquor.

2. -In arocess ofthe character described, feedin milk of lime to a pressure accumulator, eeding SOglto said accumulator, simultaneously feeding low ressure relie fluid from a digester to sai accumulator, and mixin 4the milk of lime, SO2 and low pressure re ief liquor to form slightly heatedcooking liquor in the accumulator, and afterwards introducing hi h 'pressure relief duid from a di ester into t e accumulator for increasing t e temperature and raising the pressure of said aci li ucr.

3. In a rocess o the character described, feeding milk of lime to a pressure accumulator, feedin SO2 to said accumulator, simultaneously eedinglow pressure relief fluidfrom a digester to said accumulator, and mixing the milk of lime, SO2 and low pressure re ief liquor to form slightly heated cook ing liquor in the accumulator, afterwards introducing high pressure relief fluid from a digester into the accumulator for increasing the temperature and raising the pressure of said acid liquor, and finally introducing the acid li uor thus preconditioned, into a di.- gester c arged with fibrous material for ini! tiatin the cooking of the latter.

4. Ign a process of the character described, introducing milk of lime into a pressure accumulator, introducing vaporized SO2 into said accumulator and mixin it with the milk of lime, and simultaneou y` feeding relief fluid from a digester into the accumulator.

5. In a recess of the character described, feeding mllk of lime through a passageway into a pressure accumulator, introducing va porized SO2 into said passageway and mixing the same with the milk of lime and admixing with said mixture relief fluid rom a di ester before the mixture flows into the accumu ator.

6. A process of the character described, comprising forcing milk of lime through a passageway into a pressure accumulator, introducing SO2 into said passageway and mixing the same with the milk of lime as the latter flows to the accumulator, and admixing with said mixture low pressure relief fluid from a digester.

7. In a process of the character described, flowing milk of lime through a passageway into a pressure accumulator, utilizing the flowing stream of milk of lime to assist in withdrawing lo'w pressure relief iuid from a digester and to mix said fluid with the milk of lime, and introducing vaporized SO, into the milk of lime flowing through the passageway.

8. In a process of the character described,

preparing acid liquor by mixing a suitable liquid and a vapor while the liquid flows through a passageway on the way to a pressure accumulator, and utilizing the substances forming the cooking liquor to absorb the gasecus ortion of a relief fluid from a digester.

9. n a process of the character described, introducing milk of lime into a pressure accumulator, mixing a relief fluid from a digester with the milk of lime, introducing vaporized SO2 directly into the accumulator, and mixng the same in the latter with the milk of ime.

10. In a rocess of the character described, flowing mi k of lime through a passageway into a pressure accumulator, mixing vaporized SO2 with said milk of lime, also mixing relief fluid from a digester with the milk of lime, and passing gas from the top of the accumulator back into thel lower portion of the accumulator.

11. In a process of the character described, flowing milk of lime through a passageway into a pressure accumulator, mixing vaporized SO2 with said milk of lime, also mixing relief fluid from a digester with the milk of lime, and passing gas from the top of the accumulator back into the milk of lime before the latter flows to the accumulator.

12. In a process of the character described, accumulating hot acid liquor in a pressure accumulator, and utilizing pressure in said accumulator to relieve the latter of gas and to ass said gas into milk of lime to be absor ed by the latter.

13. In a process of the character described, flowing milk of lime, vaporized SO2 and digester relief liquor to a pressure accumulator and thereby depositing in the latter somewhat preheated acid liquor, subsequently using high pressure relief fluid from a digester to increase the temperature of said acid liquor, and afterwards feeding the high temperature acid liquor into a digester charged with fibrous material.

14. An apparatus of the class described, comprising a digester, a pressure accumulator, a milk of lime tank, means for feedin milk of lime from said tank and relief flui from the digester, into the accumulator, and means for mixing vaporized SO2 with the milk of lime. i

15. In an apparatus of the character described, a pressure accumulator, a conduit for feeding milk of lime into the accumulator, a pressure tank for the storage of liquid S02, and means for vaporizing said SO2 and for feeding the resulting vapor into the accumulator.

16. In an apparatus of the character described, a digester, a pressure accumulator, a milk of lime tank, valved conduits connecting said parts, whereb relief fluid from the digester and milk of lime from the tank may be fed into the accumulator, a source of SO2, and means for mixing said SO2 with the milk of lime.

17. In an apparatus of the character described, a digester, a pressure accumulator, a milk of lime tank valved conduits connecting said parts, whereby relief fluid from the digester and milk of lime from the tank may be fed into the accumulator, a source of SO2, and means for mixing said SO2 with the milk of lime while the latter is on the way to the accumulator.

18. An apparatus of the class described, comprising an accumulator provided with a pair of down pipes, a distributor placing said down pipes in communication with the interior of the accumulator, a digester, high and low pressure relief headers connecting the upper portion of the digester to said down pipes, a milk of lime tank, means for feeding milk of lime from said tank into either one of said down pipes, a li uid SO2 tank, and conduits connecting the g 2 tank to the last mentioned means for mixing the SO2 with the milk of lime and the relief fluid while they are on the way to the accumulator.

19. In an apparatus of the character described, a pressure accumulator, a distributor for introducing fluids into the lower portion of the accumulator, a pair of feed pipes connected to said distributor, a digester, high and low pressure relief fluid headers placing the digester in communication with said pair of feed pipes, valved passageways for introducing milk of lime into said feed pipes, valved passageways for introducing vaporized S02 into said feed pipes, passageways for feeding gas from the top of the accumulator into said feed pipes, and a pressure operated valve cooperating with the last mentioned passageways.

20. In a process of the character described, flowing milk of lime, va orized SO2 and digester relief gases and iquor to a pressure accumulator and thereby depositing in the latter somewhat preheated acid li uor, subsequently using high pressure re ief fluid from a digester to increase the temperature and strength of said acid liquor and afterwards feeding the strong high temperature acid liquor into a digester charged with fibrous material.

21. In an apparatus of the character described, a digester, a pressure accumulator, a milk of lime tank, valved conduits connecting said parts, whereb relief fluid from the digester and milk of lime from the tank may be fed into the accumulator, a source of liquid SO2 under pressure, and means for mixing said SO2 with the milk of lime.

22. An apparatus of the class described, com rising a digester having a relief fluid hea er, a pressure accumulator, a pipe leading into said accumulator, a milk of lime feed conduit, and en injector Itting leading fIIom said conduit across the header into said plpe.

5 In testimony whereof, I have hereto axed my signature.

ALBERT DAvEs- MERRILL.

pig: n testimony whereof, I have hereto ailixed my signature.

ALBERT DAVIES MERRILL.

CERTIFICATE OF CORRECTION.

Patent No. 1,807,320. Granted May 26, 1931.

lt is hereby certifiedthat the middle name of the patentee in the above nu'mberedpatent was erroneously written and printed as "Davies" whereas said middle name should have been written and printed Darius; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.-

Signed and sealed thisrlth day of September, A. D. 1931.

M. J. Moore, (Seal) Acting Commissioner of P atents.

CERTIFICATE 0F CORRECTION.

Patent No. l,807,320. Granted May 26, l93l.

It is hereby certified that the middle name of the patentee in the above numbered patent was erroneously written and printed as "Davies" whereas said middle name should have been written and printed Darius; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.-

Signed and sealed this 29th day of September, A. D. 1931.

M. J. Moore, (Seal) Actingr Commissioner of Patents. 

